1. Field of Invention
The present invention relates generally to the distribution of an Ethernet stream such as video through networks. More particularly, the present invention relates to a mechanism for efficiently recovering from a failure in an optical transport network wavelength division multiplexing ring through which an Ethernet stream video may be transmitted.
2. Description of the Related Art
The use of networks such as local and metro area networks is becoming increasingly prevalent, and the rates at which data may be streamed has been increasing dramatically. For example, approximately 10 Gigabit Ethernet (GE) rates for the streaming of data are becoming more prevalent.
In synchronous optical network (SONET) and synchronous digital hierarchy (SDH) network architectures, when failures occur, the failures may be recovered fairly rapidly. That is, protection times associated with SONET and SDH networks may be relatively fast, as for example approximately fifty milliseconds (ms) or less. A protection time is an amount of time that elapses between when a failure is detected on a network path and when an alternate route for the network path may be established.
The ability to efficiently recover from failures which occur in networks that support IP and Ethernet video distribution is critical, as dropping packets of video data or significantly delaying the transmission of video data is often unacceptable. In IP and Ethernet networks, to decrease protection times associated with failure recovery, a rapid spanning-tree protocol (RSTP), as specified in IEEE 802.1w which is incorporated herein by reference in its entirety, is often utilized. A RSTP is generally effective in reducing protection times relative to a spanning-tree protocol (STP) as specified in IEEE 802.1d which is incorporated herein by reference in its entirety. However, a RSTP generally does not allow protection times of approximately fifty ms or less to be achieved.
A resilient packet ring (RPR) protocol, which is a layer 2 protocol relative to the Open Systems Interconnection (OSI) standard which is incorporated herein by reference in its entirety, initiates ring wraps in the event of a failure within a ring, e.g., a wave division multiplexing (WDM) ring, that supports 10 GE traffic. The protection mechanism associated with the RPR protocol redirects traffic to an original destination by sending the traffic in the opposite direction around the ring after a failure is detected. Though generally effective in reducing protection times to approximately fifty ms, an RPR protocol generally requires each node in a ring to implement specialized logic associated with the RPR protocol. Hence, the costs and management associated with the RPR protocol may be prohibitive. Moreover, current RPR engines which run at 10 G or more are generally not mature, and may be very expensive.
Therefore, what is needed is a method and an apparatus which allows protection times associated with a WDM ring to meet requirements for Ethernet video distribution over an IP or Ethernet network without requiring specialized logic. That is, what is desired is a system which is efficient and allows for a fast recovery to be achieved within a network that supports 10 GE traffic.